UV-C treatments extend shelf life

Recently, the increasing interest for environmentally-friendly treatments able to enhance the benefits of proper temperature management during the fruit and vegetable fresh-cut chain is driving the scientific community in developing innovative technologies for industry.

Scientists at CIDCA, Argentina have studied the efficacy of UV-C treatment in preserving the quality of fresh-cut red pepper during shelf-life.

Different UV-C doses were tested on red pepper cut into sticks (5 cm x 1 cm). After fruit peduncles and seeds were removed and the pericarp was cut, sticks were rapidly cooled to 10°C and then irradiated under a bank of 4 UV-C lamps at a distance of 30 cm (fluence rate: 17 W m-2) as follows:
a) 3, 6, 10 or 20 kJ m-2 in the inner side of the pericarp (I);
b) 3, 6, 10 or 20 kJ m-2 in the outer side of the pericarp (O);
c) 1.5, 3, 5, 10 kJ m-2 in both the inner and outer sides (I+O).

Results showed that the UV-C dose at kJ m-2 irradiated in both inner and outer pericarp sides (I+O) was the most effective in delaying the quality decay, especially the incidence of soft rot was lower (7%) than control (56% in untreated red pepper sticks).

In addition, the UV-C treatment at 10 kJ m-2 significantly reduced the fresh weight loss, softening and pectin solubilisation, without altering sugars, color, acidity and antioxidant capacity.

UV-C treated pepper sticks showed the lower respiration rate and electrolyte leakage, indicating enhanced quality maintenance. In general, UV-C treatment did not show significant antimicrobial effects, however histochemical analyses showed that the UV-C treatment enhanced the superficial accumulation of hydroxycinnamic acid-derivatives (OH-CinAD).

Table. Sugars (mg/kg), acidity (mmol H+/kg), pH, respiration rate (mg CO2/kg/h), total phenols (mg of gallic acid/kg) in control and UV-C treated (10 kJ m-2, I+O) red pepper sticks during storage at 4°C for 0, 7 and 12 days.

Present study showed that UV-C treatment at 10 kJ m-2 dose in both the inner and outer sides of the pericarp can delay the pectin solubilisation and induce a local accumulation of phenolics, thus the scientists conclude that UV-C treatment can be used by industry to enhance the efficacy of low temperatures in extending the shelf-life of fresh-cut peppers.

Source: Rodoni L.M., Zaro M.J., Hasperué J.H., ConcellónA., Vicente A.R., ‘UV-C treatments extend the shelf life of fresh-cut peppers by delaying pectin solubilisation and inducing local accumulation of phenolics’, March 2015, LWT - Food Science and Technology. http://www.sciencedirect.com/science/article/pii/S0023643815001954